Search results
Results from the WOW.Com Content Network
Data Control Language is one of the logical group in SQL Commands. SQL [1] is the standard language for relational database management systems. SQL statements are used to perform tasks such as insert data to a database, delete or update data in a database, or retrieve data from a database.
In some cases, a process to periodically sweep through and delete the obsolete versions is implemented. This is often a stop-the-world process that traverses a whole table and rewrites it with the last version of each data item. PostgreSQL can use this approach with its VACUUM FREEZE process. Other databases split the storage blocks into two ...
A common table expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement. CTEs can be thought of as alternatives to derived tables ( subquery ), views , and inline user-defined functions.
Tables can be set to inherit their characteristics from a parent table. Data in child tables will appear to exist in the parent tables, unless data is selected from the parent table using the ONLY keyword, i.e. SELECT * FROM ONLY parent_table;. Adding a column in the parent table will cause that column to appear in the child table.
Snapshot isolation is called "serializable" mode in Oracle [8] [9] [10] and PostgreSQL versions prior to 9.1, [11] [12] [13] which may cause confusion with the "real serializability" mode. There are arguments both for and against this decision; what is clear is that users must be aware of the distinction to avoid possible undesired anomalous ...
Yes - can browse table definition and data; Some - can only browse table definition; Multi-server support: Yes - can manage from the same window/session multiple servers; Some - can manage from a different window/session multiple servers; Monitoring server: Yes - includes a headless server, that runs checks and reports failures
A list of all available firing events in Microsoft SQL Server for DDL triggers is available on Microsoft Docs. [2] Performing conditional actions in triggers (or testing data following modification) is done through accessing the temporary Inserted and Deleted tables.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...